1. Make the sauce for the rice combining the vinegar, sugar, and salt.
2. Combine the sauce with the rice and allow to cool.
3. Cut the salmon and roast beef into bite size pieces.
4. Open the plastic wrap on your hand, put the salmon in the middle, add a little mustard and capers, and put a ping pong sized ball of rice on it. Twist the wrap and make a ball.
5. Grip the vinegar rice, shaping it into that of a straw bag, and cut the Shiso leaves in half, putting them on the beef and the rice.
6. Use a mix of grain mustard and soy sauce for dipping the roast beef sushi.